推送ViewController給NSInvalidArgumentException

Question

我是一個新手iOS開發人員，最近開發了幾個Android應用程序，但我不熟悉iOS的行話。讓我解釋我的問題。我想使用兩種不同的UIViewController。我爲兩個控制器創建了.h和.m文件。我的計劃是在第一個視圖控制器出現在屏幕上五秒鐘後，將第二視圖控制器推到第一視圖控制器的頂部。我的意思是第一個視圖控制器就像啓動畫面或類似的東西。

這是我的貢獻。在第一視圖控制器，I所定義（其中之一當然實現）這兩種方法：

-(void) pushSecondController { 
    SecondViewController *secondController = [[SecondViewController alloc] 
               initWithNibName: nil 
               bundle: NULL]; 
    [self.navigationController pushViewController: secondController animated: YES]; 
} 

-(void)viewDidAppear:(BOOL)animated { 
    [super viewDidAppear:animated]; 
    [self performSelector: @selector(pushViewController:animated:) 
       withObject: nil 
       afterDelay: 5.0f]; 
} 

和所述第二視圖控制器看起來像這樣：

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    self.view.backgroundColor = [UIColor whiteColor]; 
    self.title = @"Second Controller"; 
} 

我已經改變僅viewDidLoad方法。當我運行模擬器時，第一個視圖控制器運行良好，等待5秒鐘並墜毀。輸出看起來像：

2012-08-24 10:46:34.104 NavApplication[20355:f803] -[ViewController pushViewController:]: unrecognized selector sent to instance 0x6e7f780 
2012-08-24 10:46:34.107 NavApplication[20355:f803] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[ViewController pushViewController:]: unrecognized selector sent to instance 0x6e7f780' 

讓我問一個問題：我知道有methodName和methodName:之間的差異。任何人都可以解釋有什麼區別？

任何幫助，將不勝感激。

UPDATE：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{ 
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; 
    // Override point for customization after application launch. 
    self.viewController = [[ViewController alloc] initWithNibName:@"ViewController" bundle:nil]; 
    self.window.rootViewController = self.viewController; 
    self.navigationController = [[UINavigationController alloc] initWithRootViewController:self.viewController]; 
    [self.window makeKeyAndVisible]; 
    [self.window addSubview: self.navigationController.view]; 
    return YES; 
} 

Answer 1

變化@selector(pushViewController:animated:)到@selector(pushSecondController)。

Answer 2

正如上面提到的，你可能想改變你的performSelector命令：因爲你想它來調用你的pushSecondController方法

[self performSelector: @selector(pushSecondController) 
      withObject: nil 
      afterDelay: 5.0f]; 

，而不是pushViewController:animated:。

關於第二個問題：methodName和methodName:之間的差別在於，在:的methodName:結束意味着這種方法需要一個參數。所以，你可以有以下幾種方法：

- (void)listItems 
{ 
    // ... 
} 

- (void)insertItem:(NSDictionary *)item 
{ 
    // ... 
} 

時，順便提到他們進入@selector，爲你只是做@selector(listItems)第一種方法，因爲它不帶任何參數，對於後者，你會怎麼做@selector(insertItem:)，因爲它需要一個參數。

UPDATE

只看見自己的applicationDidLaunch代碼。您可能需要重新安排事項，以便將ViewController添加到UINavigationController，然後將UINavigationController設置爲窗口的rootViewController。像這樣：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{ 
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; 
    // Override point for customization after application launch. 

    self.viewController = [[ViewController alloc] initWithNibName:@"ViewController" bundle:nil]; 
    self.navigationController = [[UINavigationController alloc] initWithRootViewController:self.viewController]; 

    self.window.rootViewController = self.navigationController; 

    [self.window makeKeyAndVisible]; 
    return YES; 
} 

Answer 3

請改變你的didFinishLaunchingWithOptions方法：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
    { 
     self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; 
     // Override point for customization after application launch. 
     self.viewController = [[ViewController alloc] initWithNibName:@"ViewController" bundle:nil]; 
     self.navigationController = [[UINavigationController alloc] initWithRootViewController:self.viewController]; 

      self.window.rootViewController = self.navigationController; 

      [self.window makeKeyAndVisible]; 

      return YES; 
    }